24 DUST A CAUSE OF DISEASE. 



where, and to construct and arrange the evidence upon which I 

 wish all my statements to rest.* Should I, in doing so, tax your 

 time, or tire you with calculations, I must bespeak your indul- 

 gence ; but it shall be my endeavour to avoid this. 



Nearly all trades and manufacturing processes are attended 

 by the evolution of dust, or of volatile particles, more or less 

 considerable and more or less hurtful. 



Persons habitually breathing a dust-laden atmosphere of this 

 kind, acquire a liability to diseases of various sorts ; but as the 

 inhaled dust is necessarily, in every instance, brought into contact 

 with the lungs, it is accordingly the pulmonary organs that chiefly 

 suffer in the end. I propose, in this lecture, to direct your atten- 

 tion, as fully as time will permit, to the injurious effects of certain 

 occupations upon the health of those employed in them ; and, to 

 enable me the more succinctly to do this, I shall state what I have 

 to say under the following heads : Firstly, the effects of metallic 

 dust ; secondly, the effects of mineral dust ; thirdly, the effects 

 of vegetable dust ; fourthly, the effects of animal dust \ fifthly, 

 the effects of certain gases and volatile emanations ; sixthly, the 

 effects of constrained bodily position, conjoined with defective 

 ventilation ; seventhly, the effects of dust from poisonous metals ; 

 and eighthly, certain considerations as to the prevention of these 

 effects. 



Metallic dust is of different kinds ; and we shall speak first of that 

 which is emitted during the processes of iron and steel working. 

 You have all, doubtless, curiously watched the operations of the 

 street scissor-grinder as he plies his vocation. Each time the blade 

 touches the swiftly revolving wheel, the grinder's head, as he bends 

 over it, is enveloped in dust and sparks. Now, this peripatetic 

 steel-grinder encounters no risk from his occupation only because 

 it is carried on out of doors ; but were you to enter one of the 

 busy workshops of Sheffield, and, for a time, amid the turmoil 

 of machinery, attempt to breathe its stifling atmosphere, charged 

 with minutely pulverised dust, emitted by hundreds of wheels, 

 you would have a practical experience of the cause why few, if 

 even one, of all the workers there will ever reach their fortieth year. 

 * Vide appended Tables. 



